The pseudospark discharge is a spark-like gas discharge between electrodes having opposing holes, as described by J. Christiansen et al in Z. Phys. A290, pp. 35-41, 1979. The pseudospark discharge occurs when a certain voltage difference or gas pressure is exceeded. The breakdown characteristic of such an electrode pair shows an increasing breakdown voltage with decreasing gas pressure, a regime of operation previously well characterized as being on the left hand brand branch of the Paschen curve for gas breakdown. When a breakdown occurs, a diffuse discharge forms. The discharge can carry a high electric current of many tens of kiloamps in a single channel, without the concentrated electrode erosion that is characteristic of high pressure spark switches and vacuum switches. For this reason, the triggered pseudospark discharge switch is believed to offer the potential of very long life at high firing repetition rates.
In order to carry higher currents with faster rise times, and to distribute channel erosion over a larger area, numbers of pseudospark discharge channels have been connected in parallel, in what is termed a multi-channel pseudospark switch, or MUPS, as described by G. Mechtersheimer et al in J. Phys. E: Sci. Instrum 20, page 270, 1987. Multiple pseudospark discharge channels have been triggered simultaneously to increase the current carried. Several geometrical variants have been disclosed in the prior art. Configurations in which the channels are arranged in a line between parallel plates are disclosed in the aforementioned reference by G. Mechtersheimer et al and in U.S. Pat. No. 5,050,178 issued Sep. 17, 1991 to Bruckner et al. Configurations utilizing a compact cluster between parallel plates are disclosed by K. Frank et al, Proc. 9th Intl. Pulsed Power Conf., San Diego, 1991, pp. 472-477 and U.S. Pat. No. 5,091,819 issued Feb. 25, 1992 to Christiansen et al. A single radial array between coaxial cylindrical electrodes is disclosed in the aforementioned reference by Frank et al, and a series of radial arrays between coaxial cylindrical electrodes is disclosed in U.S. Pat. No. 5,126,638 issued Jun. 30, 1992 to Dethlefsen.
A broad range of triggering mechanisms have been employed. The pseudospark discharge can be triggered by the introduction of electrons to the vicinity of the cathode hole, as disclosed by D. Bloess et al in Nucl. Instrum. Methods 205, pp. 173-184, 1983, thereby forming a rapid closing switch for the conduction of electricity. Methods that have been employed to produce electrons for this purpose include surface discharge, as disclosed in the aforementioned reference by D. Bloess et al; injection from a pulsed glow discharge, as disclosed by G. Mechtersheimer et al, Report R103/84, Franco-German Research Institute of St. Louis, 1984; photoproduction via laser, as disclosed by G. F. Kirkman et al, Appl. Phys. Lett. 49, pp. 494-495, 1986; photoproduction via flashlamp, as described by G. Kirkman et al, Appl. Phys. Lett. 52, pp. 613-614, 1988; and surface emission from a ferroelectric, as described by H. Gundel et al, Appl. Phys. Lett. 54, pp. 2071-2073, 1989.
All of the prior art multiple channel pseudospark switches have had one or more disadvantages, including large physical size and unstable operation resulting from spontaneous discharge in the pseudospark channels. The unstable operation reduces the voltage which the switch can hold off in the open state. It is an object of the present invention to provide a stabilized pseudospark switch which overcomes some or all of the aforementioned disadvantages.